2013MNRAS.431.1220D

We use dark matter only and full hydrodynamical Constrained Local Universe Simulations of the formation of the Local Group to study the density profile of subhaloes of the simulated Milky Way and Andromeda galaxies. We show that the Einasto model provides the best description of the subhaloes' density profile, as opposed to the more commonly used Navarro, Frenk & White profile or any generalization of it. We further find that the Einasto shape parameter nE is strongly correlated with the total subhalo mass, pointing towards the notion of a non-universality of the subhaloes' density profile. We observe that the effect of mass-loss due to tidal stripping, in both the dark matter only and the hydrodynamical run, is the reduction of the shape parameter nE between the infall and the present time. Assuming now that the dwarf spheroidals (dSphs) of our Galaxy follow the Einasto profile and using the maximum and minimum values of nE from our hydrodynamical simulation as a gauge, we can improve the observational constraints on the Rmax-Vmax pairs obtained for the brightest satellite galaxies of the Milky Way. When considering only the subhaloes with -13.2 ≲ MV ≲ -8.8, i.e. the range of luminosity of the classical dwarfs, we find that all our simulated objects are consistent with the observed dSphs if their haloes follow the Einasto model with 1.6 ≲ nE ≲ 5.3. The numerically motivated Einasto profile for the observed dSphs will alleviate the recently presented `massive failures' problem.